| 摘要 |
Apparatus and methods for effectively detecting and locating explosive substances within remote targets, including improvised explosive devices (IEDs). The detection apparatus includes a thermal neutron beam generator, a gamma ray detector, data collection modules and sensors, and a detection processing module. The thermal neutron beam generator includes a fast neutron source, a neutron moderator to slow the fast neutrons to thermal neutrons, and a rotatable neutron shield enclosing the generated thermal neutrons. The neutron shield has an aperture to form a thermal neutron beam directed at a remote target. If the remote target contains explosive substances, gamma rays radiate isotropically from the remote target when it is bombarded by the thermal neutrons. A portion of these gamma rays are intercepted and detected by the gamma ray detector, which is spaced apart from the thermal neutron source in order to minimize the neutron-irradiated air path seen by the detector, thereby reducing background noise. This arrangement is known as a "bistatic" orientation. The detection processing module determines whether the remote target contains explosive substances and further locates the target by processing the collected data from the gamma ray detector and the position sensor associated with the neutron shield. More specifically, the position sensor associated with the neutron shield transmits the azimuth and elevation of the aperture to the detection processing module, which in turn determines the thermal neutron beam direction and the remote target's location. |
